Conventionally, monitors are in practical use that enable a two-parallax image photographed from two viewpoints to be stereoscopically viewed by using a special instrument such as eyeglasses for stereoscopic viewing. In recent years, monitors are also in practical use that enable, by using a light beam controller such as a lenticular lens, a multi-parallax image (such as a nine-parallax image) photographed from a plurality of viewpoints to be stereoscopically viewed by naked eyes. There are also cases in which depth information of an image photographed from one viewpoint is estimated, and the estimate information is used in image processing to generate the two-parallax image or the nine-parallax image to be displayed on the stereoscopically viewable monitor.
There are practically used medical diagnostic imaging apparatuses, such as an X-ray computed tomography (CT) apparatus, a magnetic resonance imaging (MRI) apparatus, and an ultrasonic diagnostic apparatus, that can generate three-dimensional medical image data (hereinafter called volume data). From the volume data generated by the medical diagnostic imaging apparatus, a volume rendering images (parallax images) having arbitrary parallax number at arbitrary parallax angles can be generated. Accordingly, it is studied to stereoscopically display the two-dimensional volume rendering image generated from the volume data on a stereoscopically viewable monitor that has been practically used in recent years.
However, in order to perform the volume rendering processing in real-time in response to a request from an operator, the apparatus performing the volume rendering processing is required to have a high image processing capacity.